DesignWare Technical Bulletin

Managing Design Complexity with a Complete Audio IP Subsystem

By Henk Hamoen, product marketing manager, Audio Subsystem, Synopsys

SoC designers are consistently faced with the challenge of integrating more features into their designs, with fewer resources and a shorter schedule. Through the years, we have seen consumer electronic devices require more functionality to be embedded, specifically more audio features. How can designers cope with the increase in design complexity? The answer is with a complete audio IP subsystem solution consisting of integrated hardware, dedicated software and prototyping capabilities. Figure 1 below shows the increase in the number of IP blocks in SoCs and the paradigm shift from integrating blocks to subsystems.

Figure 1: Growing number of IP blocks per SoC

Growing Complexity in AudioWith many consumer devices becoming internet connected, either via a home network (Wifi) or mobile network (e.g. 3G/4G), more audio formats (for example MP3, FLAC, Vorbis, Dolby, DTS and SRS) need to be supported . Furthermore, portable devices that can be connected via a HDMI connector to a home theater system now also need to provide multi-channel (for example 5.1) high-definition audio. While Blu-ray Disc has already increased the quality of the audio source itself, more processing is needed to create a unique sound that makes it differentiated from all other products in the market. All of these new requirements lead to the need for much higher processing capacity on the host-processor and SoC designers are now off-loading audio processing from the host-processor to dedicated audio processors.

Figure 2: Growing complexity in audio devices

Introducing the SoundWave Audio SubsystemThe DesignWare® SoundWave Audio Subsystem is a complete, pre-verified IP subsystem solution that consists of all the hardware and software needed to implement a broad range of audio functions into SoCs.

Integrated hardware components (shown in Figure 3) include highly configurable 32-bit ARC™ audio processors, digital I2S and S/PDIF interfaces for off-chip audio connections as well as high-bandwidth on-chip connections to interfaces such as HDMI. In addition, analog audio codecs provide high-quality audio connections for line inputs and outputs, microphones, loud speakers and headphones. The ARM® AMBA® AXI™/AHB protocol system interfaces help ease the integration into the SoC infrastructure.

The local interconnect includes a FlexFiFo which serves as a central data buffer that can be dynamically allocated to any of the audio peripherals, eliminating the need for separate buffers in each of the peripherals and reducing the overall area. Streaming audio data to and from audio peripherals in a SoC is traditionally a software task for the host processor, which requires a separate DMA engine for this purpose. Using the ARC audio processor, a DMA engine is no longer needed, which further reduces silicon area. Moreover, the software complexity for audio streaming is now reduced to a simple instruction on the ARC audio processor.

It’s All About the SoftwareAs more audio features and functions are implemented onto the SoC, the amount of software to support those features grows exponentially. To some extent, what truly drives the system complexity is not in the hardware itself but rather the software. Figure 1 referenced at the beginning of the article showed the paradigm shift from IP blocks to IP subsystems.

What is not shown in the figure, but also very important to this shift is the increasing amount of software required to support all of these IP blocks (which is growing at an even faster rate). At the end of the day, it is the software and the integration of that software which makes a functional SoC. A complete subsystem therefore has to include not only the hardware, but also the full software solution, or it will be of limited value.

The SoundWave Audio Subsystem consists of a complete, ready-to-use software environment that enables seamless plug-in to the host application. The integrated software stack includes a Media Streaming Framework (MSF), real-time operating system, broad portfolio of audio software codecs supporting the latest audio standards from Dolby, DTS and SRS Labs, and post-processing components. The configurable and pre-verified software components are fully integrated with the audio subsystem’s hardware. In addition, all of the features and functions of the audio subsystem are made available to the application software running on host processor via a GStreamer audio plug-in. GStreamer is a widely adapted media streaming framework for many SoC applications using Linux and Android operating systems such as digital TVs, set-top boxes and tablets.

The SoundWave Audio Subsystem includes an easy-to-use configuration tool that allows designers to quickly select options such as a single or dual-core processor, cache sizes, bus interface, number of channels and number of audio interfaces. This enables a complete audio subsystem to be configured in hours instead of weeks if done manually.

Figure 5: Fully configurable hardware and software

To ease system integration, the SoundWave Audio Subsystem includes virtual and FPGA-based prototypes to help engineering teams accelerate software development and validation of the full system. Using the same audio software that will later be used on silicon, allows application software engineers to develop their code months before the hardware design has started. Synopsys’ Virtualizer™ Virtual Prototyping tools and models allow engineers to build (model) their complete SoC and embed audio in the earliest phase of their project. The HAPS® FPGA-based prototyping solution enables system integrators to do the HW/SW co-validation of the entire design in a very easy way, also using the same audio software stack that will later be used on silicon.

Achieve Great Audio for Every SoCThe SoundWave Audio Subsystem is the industry’s first complete audio IP subsystem available to SoC designers. By providing integrated hardware, a complete software stack and prototyping in a pre-verified, SoC-ready audio subsystem solution, Synopsys enables designers to significantly reduce their design and integration effort, lower risk and accelerate time-to-market.